Jump to content


Photo

Hit RA limit stop

lx600

  • Please log in to reply
7 replies to this topic

#1 cgordo5

cgordo5

    Advanced Member

  • Members
  • PipPipPip
  • 38 posts

Posted 02 October 2013 - 08:47 AM

Hi,

I was photographing the Andromeda galaxy last night when it was high in the sky but still in the eastern part of the sky. I saw the Starlock lose its lock and then I heard a faint noise. When I looked at my image, I saw that the telescope had stopped tracking. Then I realized that the problem was that the telescope had hit the RA stop. There was no warning or any kind of error message.

I'm glad I was only doing a short exposure and that I was near the telescope. I would think that had this gone on for 10 or 20 minutes or more it could cause damage.

It seems like the stop is in an inconvenient position. It is usually desirable to photograph near the zenith.

Has anyone else hit this problem? Is there any way to change the stop position?

Thanks,
Charles

#2 gspie

gspie

    Advanced Member

  • Members
  • PipPipPip
  • 314 posts
  • LocationScottsdale, Arizona

Posted 02 October 2013 - 02:33 PM

That's the problem with fork mounts. I had one with my LX-200 classic. I could not image above about 58-degrees dec.
The only way to get higher is to reduce your imaging chain - no filter wheel, no focal reducer, shorter camera.

That is why I went to the LX-850 (or any scope with a German Eq. Mount). It also has issues when an object crosses the meridian, but that can be dealt with fairly easily. The fork issue is limiting, and unless someone come up with some sort if fork extender, you're up that creek.
LX850 with 10" ACF OTA and Takahashi FS 60C OTA -- SBIG STT-8300M CCD with FW8G-STT Self Guiding Filter Wheel and SBIG AO-8 Adaptive Optics -- Camera Control and Image Calibration with Maxim DL/CCD Pro, Image processing with PixInsight, and final composition with Photoshop CS5

http://home.comcast....ie/astroweb.htm

#3 cgordo5

cgordo5

    Advanced Member

  • Members
  • PipPipPip
  • 38 posts

Posted 02 October 2013 - 06:52 PM

I guess I should have explained better. I have the X Wedge. The telescope is not hitting anything externally. It is getting to the internal RA stop which doesn't allow the telescope to fully rotate in RA. The only way to get around it is to rotate the scope fully in the opposite direction in RA and start again from there.

Charles

#4 gspie

gspie

    Advanced Member

  • Members
  • PipPipPip
  • 314 posts
  • LocationScottsdale, Arizona

Posted 03 October 2013 - 12:20 AM

That sounds like what happens with a GEM - it may think it is rotating past meridian and will require pier flip. Check the slew limits (if the controller has them), there are several telescope settimgs , one of which may fix it. I don't have the LX600 manual. See of there is a max past meridian setting
LX850 with 10" ACF OTA and Takahashi FS 60C OTA -- SBIG STT-8300M CCD with FW8G-STT Self Guiding Filter Wheel and SBIG AO-8 Adaptive Optics -- Camera Control and Image Calibration with Maxim DL/CCD Pro, Image processing with PixInsight, and final composition with Photoshop CS5

http://home.comcast....ie/astroweb.htm

#5 jrcrilly

jrcrilly

    Advanced Member

  • Members
  • PipPipPip
  • 51 posts

Posted 03 October 2013 - 02:56 AM

The advantage of a wedged fork is that you can image right on through meridian and on to the horizon. The RA hard stops are more than 360 degrees apart so you should never be in danger of hitting one if the mount is correctly positioned initially. It sounds like you started with the mount oriented North but near one stop rather than using the North position that is halfway between the stops.

#6 tlwarnke

tlwarnke

    Advanced Member

  • Members
  • PipPipPip
  • 54 posts

Posted 03 October 2013 - 04:39 AM

I agree with jrcrilly. Make sure you are half way between hard stops by releasing the RA clutch and manually spinning the forks to one stop then back to the other counting the rotations between stops. Then move back half the turns.

Terry

#7 cgordo5

cgordo5

    Advanced Member

  • Members
  • PipPipPip
  • 38 posts

Posted 03 October 2013 - 11:32 AM

Thanks for the advice. I checked this morning and the scope will turn about 1.75 complete rotations with the clutch unlocked. Looks like I need to be careful to use the right home position (there are a couple possible) when I align it.

Charles

#8 jrcrilly

jrcrilly

    Advanced Member

  • Members
  • PipPipPip
  • 51 posts

Posted 03 October 2013 - 11:37 AM

Thanks for the advice. I checked this morning and the scope will turn about 1.75 complete rotations with the clutch unlocked. Looks like I need to be careful to use the right home position (there are a couple possible) when I align it.

Charles


Yup - that's the key. You shouldn't have any more problems with the stops.





Also tagged with one or more of these keywords: lx600

0 user(s) are reading this topic

0 members, 0 guests, 0 anonymous users